The issue becomes clear if you notice its hierarchical structure. I'll quote myself to prevent re-writing a childish example:
And yet, if everyone in the world who owns bitcoin was only interested in holding it in their own wallet because it might be worth more in the future, and never spent it, sold it, traded it, gambled it, used it, transacted with it, etc., then it would be worth nothing.
Bitcoin is a currency first and foremost. Global adoption is not going to achieved due to global speculation as you focus on; it will be achieved due to global use. In places like Venezuela where they are experiencing hyperinflation of their fiat currency, bitcoin is already vital tool and currency for the average person not just to protect their wealth, but to able to survive.
Each bitcoin carries 8 decimal places. 1 bitcoin is 1.00000000. This format defines bitcoin's potential for future growth. As the value of bitcoin increases, transactions will move further to the right of the decimal point.
This is not a hard limit. More decimal places can be introduced if required, and Lightning already works with 11 decimal places with the smallest unit being the milli-satoshi.